1. Field
The present application relates generally to wireless communications, and more specifically to methods and systems for acquisition of time and location information by AP base stations.
2. Background
Wireless communication systems are widely deployed to provide various types of communication (e.g., voice, data, multimedia services, etc.) to multiple users. As the demand for high-rate and multimedia data services rapidly grows, there lies a challenge to implement efficient and robust communication systems with enhanced performance.
In recent years, users have started to replace fixed line communications with mobile communications and have increasingly demanded great voice quality, reliable service, and low prices. In addition to mobile phone networks currently in place, a new class of small base stations has emerged, which may be installed in residential or business locations to provide indoor wireless coverage to mobile units using existing broadband internet connections. Such personal miniature base stations are generally known as an access point (AP) base station, also referred to as Home Node B (HNB) unit, femto cell, femto base station (fBS), base station, or base station transceiver system (BTS). Typically, such miniature base stations are connected to the internet and the mobile operator's network via a digital subscriber line (DSL) router or cable modem.
AP base stations or femto cells allow for cellular access where base station support is weak or unavailable (e.g., indoors, remote locations, and the like). AP base stations may be described as small base stations that connect to wireless service providers via a broadband backhaul link, such as DSL, cable internet access, T1/T3, etc., and offer typical base station functionality, such as base transceiver station (BTS) technology, radio network controller, and gateway support node services. This allows an access terminal (AT), also referred to as a cellular/mobile device or handset, or user equipment (UE), to connect to the AP base stations and utilize the wireless service. It is noted that ATs can include, for example, cellular phones, smart phones, laptops, handheld communication devices, handheld computing devices, satellite radios, navigational devices, personal digital assistants (PDAs), and/or any other suitable device for communicating over a wireless communication system.
AP base stations generally need accurate time synchronization with the mobile operator's network, as well as accurate frequency reference for generation of radio frequency carrier and sampling clocks. AP base stations also need accurate information about their position in order to satisfy operational and regulatory requirements of the jurisdictions in which they operate, as well as to support location-based services provided by cellular networks. However, the acquisition of network time and frequency or position determination by AP base stations are often complicated by radio frequency (RF) isolation and/or hidden node issues associated with the deployment of AP base stations in residential and commercial environments, typically in the interior of buildings. Accordingly, it would be desirable to provide a technique for AP base stations to utilize available information resources to obtain accurate estimates of time and frequency references, and position, and to implement fall back modes of operation when it is not possible to acquire signals used for navigation.